System for balancing battery pack system modules

ABSTRACT

A system for balancing a plurality of battery pack system modules connected in series comprising: a plurality of battery pack system modules, wherein a high charge module of the plurality of battery pack system modules has a charge greater than a that of other modules. At least one zener diode connected in series with a current limiting resistor is connected in parallel to the plurality of battery pack system modules. A power source is in communication with a disconnect circuit of at least one of the battery pack system modules. The disconnect circuit is actuated when the battery pack system module reaches a predetermined state of charge. The zener diode enables current from the power source to bypass charged battery pack system modules to charge other battery pack system modules.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to co-pending U.S. ProvisionalApplication Ser. No. 61/054,882 filed on May 21, 2008, entitled “Systemfor Balancing Battery Pack System Modules” and is incorporated herein.

FIELD

The present embodiments generally relate to a system for balancing aplurality of battery pack system modules.

BACKGROUND

A need exists for a system for balancing battery pack system modulesthat balances states of charge of the battery pack system modulesautomatically, without requiring manual balancing during maintenanceoperations.

A further need exists for a system for balancing battery pack systemmodules in which each battery pack system module is independentlyself-balancing, without requiring communication with a master controlleror other battery pack system modules, obviating the need for a costlycentralized master controller, and the need for complex interconnectionbetween battery pack system modules.

A need also exists for a system for balancing battery pack systemmodules that enables individual battery pack system modules and groupsof battery pack system modules to be selectively removable andreplaceable, without interrupting charging of other battery pack systemmodules.

The present embodiments meet these needs.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description will be better understood in conjunction withthe accompanying drawings as follows:

FIG. 1 depicts a diagram of an embodiment of a battery pack systemmodule useable with the present system.

FIG. 2 depicts a diagram of an embodiment of the present systemcontaining battery pack system modules connected in series, each havinga zener diode.

FIG. 3 depicts a diagram of an embodiment of the present systemcontaining groups of battery pack system modules connected in parallel,that are connected to other groups of battery pack system modules inseries.

FIG. 4 depicts a diagram of an embodiment of the present systemcontaining groups of battery pack system modules connected in series,that are connected to other groups of battery pack system modules inparallel.

FIG. 5 depicts a diagram of an embodiment of a method useable with anembodiment of the present system.

FIG. 6 depicts a diagram of an embodiment of a method useable with analternate embodiment of the present system.

The present embodiments are detailed below with reference to the listedFigures.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Before explaining the present system in detail, it is to be understoodthat the system is not limited to the particular embodiments and that itcan be practiced or carried out in various ways.

The present embodiments relate to a system for balancing a plurality ofbattery pack system modules, which can be connected in series. Thepresent system can also be useable to balance multiple groups of batterypack system modules connected in parallel. Each group of parallelbattery pack system modules can be connected to other groups of batterypack system modules in series.

In conventional systems, when a single battery pack system module withina system of battery pack system modules connected in series reaches apredetermined state of charge, a disconnect circuit within the batterypack system module is actuated, preventing current from charging anyother battery pack system modules within the battery pack system.

This inability to charge other battery pack system modules can result inunbalanced battery pack systems, which can cause damage to the batterypack system modules and other equipment connected to the battery packsystem. Additionally, the existence of overcharged and unbalancedbattery pack system modules can present a safety hazard to personnelthat operate on the battery pack system modules and any attachedequipment.

Conventional battery pack system modules connected in series musttherefore be balanced manually, by interrupting operation of equipmentpowered by the battery pack system, fully discharging each battery packsystem module within the battery pack system, then simultaneouslycharging each battery pack system module. Manual balancing operationsare tedious, time consuming, and costly, and are therefore typicallyundertaken no more often than once every six months.

These special maintenance operations are often not performed due toinattention to detail or a lack of time, manpower, or other resourcesnecessary to perform the manual balancing operations. Failure to performthese balancing operations can allow individual battery pack systemmodules within a group of modules connected in series to attainunbalanced states of charge, potentially damaging one or more parts ofthe modules and any connected equipment, and creating a safety hazard tooperators of the battery pack system modules and connected equipment.

The present system advantageously enables a plurality of battery packsystem modules, which can be connected in series to independently andautomatically attain a balanced state of charge during a normal chargephase, without requiring separate special maintenance operations.Through use of the present system, the costly and time consuming needsfor manual balancing of the battery pack system modules is removedentirely.

The present system can use zener diodes connected in series with currentlimiting resistors to enable current from a power source toautomatically bypass battery pack system modules that have attained apredetermined state of charge. By enabling the bypass of charged batterypack system modules, the zener diodes enable the charging of otherbattery pack system modules connected in series within a system thathave not yet attained the predetermined state of charge. The presentsystem thereby automatically creates a balanced state of charge withinthe battery pack system once each battery pack system module hasattained the predetermined state of charge.

Additionally or alternatively, the present system can utilize computerinstructions for measuring the state of charge of a battery pack systemmodule, disconnecting a charge switch, and actuating shunt resistorswithin balancing circuits to partially discharge battery pack systemmodules that have attained a predetermined high state of charge. Theshunting of the battery pack system modules can be performed until themodules reach a hysteresis state of charge, at which time the chargeswitch can be reconnected, and charging of the battery pack system canresume.

By automatically partially discharging battery pack system modules thathave reached the predetermined high state of charge, the simultaneouscharging of each module within a battery pack system can be continuedwithout exceeding the predetermined high state of charge in any batterypack system module.

This embodiment of the present system produces an oscillating state ofcharge within the battery pack system modules, whereby once a batterypack system module has attained a predetermined high state of charge,the battery pack system module is partially discharged, then chargedsimultaneously with other battery pack system modules connected inseries. Once all battery pack system modules within a battery packsystem are charged to the predetermined high state of charge, creating abalanced system, it can be contemplated that all of the battery packsystem modules exhibit an oscillating state of charge simultaneously,through partial discharge using the balancing circuits, thensimultaneous charging from a power source.

It is contemplated that in an embodiment, the use of computerinstructions to automatically cause the partial discharge of batterypack system modules that have reached a predetermined high state ofcharge can be coupled with use of zener diodes connected to currentlimiting resistors. Using this embodiment, during discharge of a chargedbattery pack system module, current can continue to charge other batterypack system modules connected in series by bypassing the dischargingmodule through use of a zener diode, providing enhanced efficiency overthe use of zener diodes or partial discharge alone.

The present system can provide the advantage of enabling constant andcontinuous balancing of a plurality of battery pack system modulesconnected in series, automatically, each time a battery pack system ischarged. Typical balancing operations are only performed once every sixmonths, or even less frequently, generating a greater risk that abattery pack system will become unbalanced as time passes.

By enabling automatic balancing of a plurality of battery pack systemmodules connected in series, use of a battery pack system modulebalancing resistor, typically required for conventional balancingoperations, is not necessary. Attachment of a balancing resistor can bedisruptive to normal operation of a battery pack system.

Conventional systems require that each battery pack system module withina system communicates with one another through complex interconnections,or through a costly centralized master controller. The present systemcan enable each battery pack system module to independently attain abalanced state of charge with other battery pack system modulesconnected in series, without requiring centralized monitoring orcontrol, and without requiring any of the battery pack system modules tocommunicate with any other module.

The present system thereby provides the benefit of increased batterypack system design flexibility, while retaining battery pack systemmodule balance. Because each battery pack system module can beindependent of one another, battery pack system modules within a batterypack system can be removed and reconfigured in a modular fashion,allowing nearly unlimited flexibility in battery pack system designconfigurations.

The present system further provides the advantage of enabling batterypack system modules to be charged to a predetermined state of charge,such as about 80 percent of the maximum capacity for each battery packsystem module. By permitting balancing of battery pack system modules atselected predetermined states of charge, the lifespan of cells withineach battery pack system module can be prolonged significantly. Typicalrechargeable cells can be fully charged to their maximum capacity, thenfully discharged, approximately 1,000 times. By charging and balancingat a predetermined state of charge, using the present system, each cellcan be contemplated to have a life expectancy ranging from about 2,000charging cycles to about 10,000 charging cycles, or more.

Additionally, maintaining a battery pack system module's cells at apredetermined level of charge, such as about 80 percent of maximumcapacity, can increase useable life for a battery pack system moduleused in a mode where there are infrequent charge/discharge cycles, suchas a back-up mode, from a typical useable life of about 1 year to about2 years to a greater useable life of about 5 years to about 10 years.

Referring now to FIG. 1, a diagram of an embodiment of a battery packsystem module useable with the present system is depicted.

The battery pack system module is depicted having a battery pack controlmodule (6), which is useable to internally monitor and balance states ofcharge of a plurality of individual cells connected in series within thebattery pack system module. The battery pack control module (6) is alsouseable to monitor and balance groups of cells connected in parallel,the groups of cells connected to other groups of cells in series.

The battery pack control module (6) includes a controller assembly (8)for measuring parameters and controlling a disconnect circuit (12) andbalancing circuits (25 a, 25 b) responsive to parameters measured by thecontroller assembly (8) and a pack sensing circuit (21).

A voltage regulator (42), such as a DC programmable voltage regulatormade by Linear Technology, Inc. of Malpitas, Calif., can be used topower the controller assembly (8).

The battery pack control module (6) is shown having a protective diode(28), which can be a reverse voltage protection diode or a bypass diode,useable to protect cells within the depicted battery pack system modulefrom excessive voltage. Bypass diodes such as those manufactured by ONSemiconductor of Phoenix Ariz. or Vishay of Malvern, Pa. can becontemplated for use herein. The protective diode (28) can be connectedto the disconnect circuit (12), and to a first group of cells (20).

For example, the protective diode (28) can prevent damage to thedisconnect circuit (12) by shunting damaging negative voltage transientsaround the disconnect circuit (12).

The disconnect circuit (12) is depicted having a charge switch (13) anda discharge switch (14), which can be transistor switches, such as aVishay P-FET switch, made by Vishay of Malvern, Pa., or similar types ofswitches. The disconnect circuit (12) can be in communication with asecond group of cells (19).

The first group of cells (20) is shown having a first lithium ion cell(17) and a second lithium ion cell (18), which can be connected inparallel. The first group of cells (20) can be connected in series tothe second group of cells (19). The second group of cells (19) is shownhaving a third lithium ion cell (15) and a fourth lithium ion cell (16),which can be connected in parallel.

While each group of cells (19, 20) is shown including two individualcells connected in parallel, it is contemplated that a group of cellscan have any number of cells, such as from about one cell to about fourcells, or more.

FIG. 1 depicts each of the cells (15, 16, 17, 18) as lithium ion cells,such as lithium ion cells having a nominal voltage of about 3.7 voltsmade by Tianjin Lishen Battery Joint-Stock Co. Ltd., of Tianjin Huayuan,China. It can be contemplated that the present system can be useablewith any type of rechargeable cell, including nickel cadmium cells,nickel metal hydride cells, lead acid cells, and other similarrechargeable cells.

In an embodiment, one or more battery pack system modules can includeone or more capacitors, one or more supercapacitors, one or moreelectrochemical cells, such as fuel cells, or combinations thereof, inaddition to the plurality of cells (15, 16, 17, 18). The one or morecapacitors, one or more supercapacitors, one or more electrochemicalcells, or combinations thereof can also be included in place of theplurality of cells (15, 16, 17, 18).

A zener diode (49), such as a high power zener diode manufactured by ONSemiconductor of Phoneix, Ariz., can be connected in series with acurrent limiting resistor (51), such as a current limiting resistorhaving a power capability of five watts or more, manufactured by Vishayof Malvern, Pa. The zener diode (49) and current limiting resistor (51)can be connected in parallel to the protective diode (28) and can be incommunication with the disconnect circuit (12).

It is contemplated that the zener diode (49) and current limitingresistor (51) can be disposed between adjacent battery pack systemmodules within a group of battery pack system modules connected inseries. The zener diodes can be contemplated to permit the flow ofcurrent from a power source, shown in FIG. 1 as a charger (48) through abattery pack system module that has reached a predetermined state ofcharge without charging the battery pack system module, thereby allowingthe charging of other battery pack system modules connected in series.

The zener diode (49) can permit the flow of current that would otherwisebe stopped by actuation of the disconnect circuit (12), enablingcharging of other battery pack system modules connected in series withthe depicted battery pack system module. For example, when thedisconnect circuit (12) is actuated, a current of 250 ma can bepermitted to flow through the current limiting resistor (51) and thezener diode (49) to charge one or more adjacent battery pack systemmodules.

The controller assembly (8) is shown having an analog controller (9),such as Part Number BQ29312A, available from Texas Instruments ofDallas, Tex., and a digital controller (10). The digital controller (10)can include analog and digital input/output ports, a processor, whichcan be a microprocessor, memory, which can include flash memory andprocessing logic located in the memory, and computer instructions forexecuting balancing, measuring, charging, and discharge functions.

The analog controller (9) is shown having a measuring device (24), whichcan be contemplated to measure the voltage of individual cells or groupsof cells within the battery pack system module, or the voltage of theentire battery pack system module.

The controller assembly (8) can be in communication with the packsensing circuit (21), which is shown having a current measuring device(23) and a temperature measuring device (22). The voltage, current, andtemperature measurements obtained using the measuring devices (22, 23)can be used by the digital controller (10) to obtain the state of chargeof the battery pack system module. The state of charge can be related tovoltage, current, and/or temperature as relative capacity through datatables within configuration memory (46).

It is contemplated that the pack sensing circuit (21) can measuretemperatures ranging from about −50 degrees Centigrade to about 85degrees Centigrade or more, current ranging from about 0 ma to about16,000 ma or more, and voltage ranging from about 0 V to 18 about V ormore.

The state of charge indicates the percent charge of the battery packsystem module relative to the nominal maximum charge of the battery packsystem module. The state of charge can also be measured as absolutecapacity by additionally measuring the time average current into and outof the entire battery pack system module to obtain the number ofamperage hours remaining in the battery pack system module.

In an embodiment, the measured state of charge of the battery packsystem module can be an absolute state of charge determined by countingcoulombs, such as an absolute capacity of 24 ampere hours based on theflow of coulombs from a power source.

The state of charge and status of the battery pack system module can beacquired and externally displayed using an initializer or display device(50), such as a monitor made by Hewlett Packard of Palo Alto, Calif.,which can be in communication with the controller assembly (8).

The state of charge and status of the battery pack system module can beexternally displayed using an external display device (5). The externaldisplay device (5) can include one or more light emitting diodes, suchas 4 mm oval red LEDs made by Ledman Optoelectronic Co., Ltd., ofChina., a liquid crystal display, such as one made by Sony Electronics,Inc., a plasma display, such as one made by Ningbo Boigle DigitalTechnology Co., Ltd., of China, or combinations thereof. Use of a liquidcrystal display can be contemplated to be advantageous for applicationswhen lower power consumption is required, such as military applications.

An internal display (11), a liquid crystal display, a plasma display, orcombinations thereof can be in communication with the controllerassembly (8). The internal display (11) and the external display (5) canbe useable separately or together to visibly display status and capacityparameters of the battery pack system module for use by operators andother users.

A first balancing circuit (25 a) is shown having a first shunt resistor(26 a) and a first by-pass switch (27 a) can be in communication withthe controller assembly (8) and the first group of cells (20). A secondbalancing circuit (25 b) is shown having a second shunt resistor (26 b)and a second by-pass switch (27 b) can be in communication with thecontroller assembly (8) and the second group of cells (19). The by-passswitches (27 a, 27 b) can include semiconductor switches, variableresistors, mini-micro switches, or combinations thereof.

The balancing circuits (25 a, 25 b) can be contemplated to be useable tobalance the states of charge of the groups of cells (19, 20). Thebalancing circuits (25 a, 25 b) can also be contemplated to be useableto at least partially discharge the depicted battery pack system moduleto facilitate balancing of a plurality of battery pack system modulesconnected in series.

FIG. 1 depicts a power source (48), which is shown as a charger,connected to the first group of cells (20) and to the disconnect circuit(12). The power source (48) can include any type of current limited andvoltage limited power source, including one or more solar panels, fuelcells, or any other current limited power supply with voltage foldback,such as a Lambda GENH 40-19 or the equivalent.

The controller assembly (8) can include computer instructions (44),which can be stored in flash memory or using other means, forinstructing the processor of the digital controller (10) to actuate andde-actuate the disconnect circuit (12) in response to voltage, current,and temperature measurements obtained from the measuring devices (22,23, 24).

The computer instructions (44) can also instruct the processor of thedigital controller (10) to actuate and de-actuate the balancing circuits(25 a, 25 b) and the disconnect circuit (12) to balance states of chargeof the groups of cells (19, 20), allowing the safe charge and internalbalancing of the cells within the depicted battery pack system module.

The controller assembly (8) can further includes configuration memory(46), such as flash memory, that can be loaded by the initializer ordisplay device (50), that can contain battery pack system module designparameters, such as cell chemistry parameters, application parameters,charge parameters, discharge parameters, and other similar parameters.The provision of the configuration memory (46) can enable the designingof battery pack system modules with unique specifications andcharacteristics.

The controller assembly (8) can further includes computer instructions(45), which can be stored in flash memory, or using other means, whichcan be used to balance the state of charge of the depicted battery packsystem module with that of other battery pack system modules connectedto the depicted battery pack system module in series.

The computer instructions (45) can be contemplated to instruct theprocessor of the digital controller (10) to measure the state of chargeof the battery pack system module using one or more of the measuringdevices (22, 23, 24) and display the state of charge on the initializeror display device (50).

The computer instructions (45) can also instruct the processor of thedigital controller (10) to actuate and de-actuate the charge switch (13)of the disconnect circuit (12) when the battery pack system modulereaches a predetermined state of charge. For example the charge switch(13) can be actuated when a solar cell battery reaches a predeterminedstate of charge of about 80 percent to about 85 percent relativecapacity, the predetermined charge selected to prolong the life of thebattery.

The computer instructions (45) can further instruct the processor of thedigital controller (10) to actuate and de-actuate the by-pass switches(27 a, 27 b) of each of the balancing circuits (25 a, 25 b) when thebattery pack system module reaches the predetermined state of charge,thereby at least partially discharging the battery pack system moduleusing the shunt resistors (26 a, 26 b)

The present system thereby can utilize the shunt resistors (26 a, 26 b)for the dual purposes of balancing the state of charge of individualcells within the battery pack system module, and for at least partiallydischarging all cells of the battery pack system module to balance thestate of charge of the battery pack system module with that of otherbattery pack system modules connected in series.

The computer instructions (45) can be contemplated to actuate the shuntresistors (26 a, 26 b) of each balancing circuit (25 a, 25 b) when thebattery pack system module is charged to a predetermined high state ofcharge, causing discharge of the battery pack system module, and tode-actuate the shunt resistors (26 a, 26 b) to cease the discharge ofthe battery pack system module when the battery pack system module hasbeen discharged to a predetermined hysteresis charge.

For example, when a battery pack system module reaches a predeterminedhigh state of charge of about 85 percent relative capacity, eachbalancing circuit within the battery pack system module can be actuatedto discharge the battery pack system module to a hysteresis charge ofabout 83 percent relative capacity, at which time the balancing circuitscan be de-actuated to cease discharge of the battery pack system module.

Referring now to FIG. 2, a diagram depicting an embodiment of thepresent system is shown.

FIG. 2 depicts a battery pack system (40), which can include a pluralityof battery pack system modules. FIG. 2 shows a first battery pack systemmodule (202 a) connected in series with a second battery pack systemmodule (202 b), and a third battery pack system module (202 c).

While FIG. 2 depicts the battery pack system (40) is shown having threebattery pack system modules, it can be contemplated that a battery packsystem can include any number of battery pack system modules, such asfrom about 1 battery pack system module to about 15 battery pack systemmodules, or more, depending on the voltage requirements of the system.

For example, when a voltage of 200 volts is required in an automobile, asufficient number of battery pack system modules connected in series, orgroups of battery pack system modules connected in parallel that areconnected to other groups in series can be provided, that provide atotal nominal voltage of at least 200 volts.

Each battery pack system module (202 a, 202 b, 202 c) can include anynumber of individual cells. In an embodiment, from about one cell toabout four cells connected in series can be contained in each batterypack system module, such that each battery pack system module provides anominal voltage ranging from about 3.7 volts to about 14.8 volts. Whenfully charged, each battery pack system module can provide from about4.2 volts to about 16.8 volts, and when empty, from about 3 volts toabout 12 volts.

It can be contemplated that one battery pack system module of theplurality of battery pack system modules can be a high charge module,having reached a predetermined level of charge greater than that ofother battery pack system modules, such as by about 1 percent to about50 percent or more when a system is extremely unbalanced, by about 1percent to about 20 percent when a system is significantly unbalanced,or about 1 percent to about 5 percent when a system is moderatelyunbalanced. The predetermined level of charge can be the maximum levelof charge for the battery pack system module, or another level specifiedby a user and/or manufacturer, such as about 80 percent relativecapacity for the battery pack system module.

For example, a high charge battery pack system module (202 a) can becharged to a predetermined high state of charge of about 90 percentrelative capacity, while an adjacent battery pack system module (202 b)can have a charge of about 89 percent relative capacity, and the nextadjacent battery pack system module (202 c) can have a charge of about60 percent relative capacity.

In this situation, current from a charger (48) conducted to the highcharge battery pack system module (202 a) can bypass the high chargebattery pack system module (202 a) via a zener diode contained withinthe high charge battery pack system module (202 a) to charge theadjacent battery pack system modules (202 b, 202 c). When the secondbattery pack system module (202 b) has reached the predetermined levelof about 90 percent relative capacity, current from the charger (48) canbypass the second battery pack system module (202 b) via a zener diodecontained within the second battery pack system module (202 b) to chargethe third battery pack system module (202 c).

Referring now to FIG. 3, a diagram depicting an alternate embodiment ofthe present system is shown.

FIG. 3 depicts a first group of battery pack system modules (40 a),which can include a first battery pack system module (202 a) and asecond battery pack system module (202 b) connected in parallel.

FIG. 3 also depicts a second group of battery pack system modules (40b), which can include a third battery pack system module (202 c) and afourth battery pack system module (202 d) connected in parallel.

The first group of battery pack system modules (40 a) can be connectedin series with the second group of battery pack system modules (40 b).

While FIG. 3 depicts two groups of battery pack system modules connectedin series, each group containing two battery pack system modulesconnected in parallel, it can be contemplated that each group caninclude any number of battery pack system modules connected in series orin parallel, and that any number of groups of modules can be in turnconnected in series or in parallel.

FIG. 3 depicts a charger (48) for providing current to each of thebattery pack system modules (202 a, 202 b, 202 c, 202 d). In theembodiment, it is contemplated that each battery pack system module canlack a zener diode. It can be contemplated that each battery pack systemmodule can include balancing circuits having shunt resistors. Computerinstructions can be within each battery pack system module and can causethe shunt resistors to be actuated when the battery pack system modulereaches a predetermined level of charge, causing the battery pack systemmodule to be at least partially discharged.

After partial discharge of the battery pack system module, current fromthe charger (48) can again simultaneously charge each of the batterypack system modules (202 a, 202 b, 202 c, 202 d) until one or more ofthe battery pack system modules reaches the predetermined state ofcharge.

For example, if the first and second battery pack system modules (202 a,202 b) reach a predetermined state of charge of about 90 percentrelative capacity, prior to the third and fourth battery pack systemmodules (202 c, 202 d), which have reached about 82 percent relativecapacity, the first and second battery pack system modules (202 a, 202b) can be partially discharged by a predetermined amount, automatically,through use of computer instructions to actuate balancing circuits.

The first and second battery pack system modules (202 a, 202 b) can bedischarged to a hysteresis value of about 86 percent relative capacity.Then, charging of the entire battery pack system could be resumed, untilthe first and second battery pack system modules (202 a, 202 b) againreach about 90 percent relative capacity, while the third and fourthbattery pack system modules (202 c, 202 d) reach about 86 percentrelative capacity.

The first and second battery pack system modules (202 a, 202 b) canagain be discharged to about 86 percent relative capacity, and chargingof the entire battery pack system would continue until each battery packsystem module (202 a, 202 b, 202 c, 202 d) reaches the predeterminedstate of charge of about 90 percent relative capacity. All four batterypack system modules (202 a, 202 b, 202 c, 202 d) can then be balancedand would proceed to charge to the predetermined 90 percent capacity anddischarge to about 86 percent capacity together, until the charger (48)is disconnected.

Referring now to FIG. 4, a diagram depicting an alternate embodiment ofthe present system is shown.

FIG. 4 depicts a first group of battery pack system modules (40 a),which can include a first battery pack system module (202 a) and asecond battery pack system module (202 b) connected in series.

FIG. 4 also depicts a second group of battery pack system modules (40b), which can include a third battery pack system module (202 c) and afourth battery pack system module (202 d) connected in series.

The first group of battery pack system modules (40 a) can be connectedin parallel with the second group of battery pack system modules (40 b).

A charger (48) is shown for providing current to each group of batterypack system modules (40 a, 40 b) simultaneously.

It can be contemplated that the design flexibility provided by thepresent system enables any number of battery pack system modules to bestackable, and to be connected in any number of series and/or parallelconfigurations to provided a desired amount of voltage.

It can further be contemplated that the design flexibility provided bythe present system can enable any individual battery pack system moduleof similar design to be independently removed and replaced, and selectedgroups of battery pack system modules to be independently removed andreplaced.

Referring now to FIG. 5, a diagram showing an embodiment of a methoduseable with an embodiment of the present system is shown.

FIG. 5 depicts that current can be provided to a battery pack systemcontaining multiple battery pack system modules until a first batterypack system module reaches a predetermined state of charge (300).

Once the first battery pack system module reaches a predetermined stateof charge, a discharge switch in the first battery pack system modulecan be opened to prevent further charging of the first battery packsystem module (302).

Current from the charger can be carried to other battery pack systemmodules in the battery pack system using a zener diode within the firstbattery pack system module (304), thereby enabling the remaining moduleswithin the battery pack system to continue charging when the firstbattery pack system module has been disconnected from the charger.

Charge switches in other battery pack system modules can be opened whenthe other battery pack system modules reach the predetermined state ofcharge (306).

Zener diodes within each charged battery pack system module can be usedto carry the current of the battery pack system modules that havereached the predetermined state of charge, so that the battery backsystem can continue to be charged until the entire system has reachedthe predetermined state of charge (308).

FIG. 6 depicts a diagram showing an embodiment of a method useable withan alternate embodiment of the present system.

FIG. 6 depicts that current can be provided to a battery pack systemcontaining multiple battery pack system modules until a first batterypack system module reaches a predetermined high state of charge (400).

Computer instructions can be within the first battery pack system moduleand can then be used to disconnect the charge switch and to actuateshunt resistors within the first battery pack system module to at leastpartially discharge the first battery pack system module to apredetermined hysteresis state of charge (402). This action can preventbattery pack system module cells from over charging and provides forinitiation of charge/discharge cyclic oscillation.

Continued charging of the first battery pack system module is therebyable to be resumed, then stopped as the first battery pack system moduleis at least partially discharged in a cyclic charge/dischargeoscillating fashion, such that the first battery pack system moduleoscillates between the predetermined high state of charge and thehysteresis state of charge continuously, as long as a charge source isconnected.

Other battery pack system modules that have not obtained thepredetermined high state of charge can be charged but not dischargeduntil each reaches the predetermined high state of charge (404).

At that time, computer instructions can be used to actuate shuntresistors within each battery pack system module to at least partiallydischarge each battery pack system module that reaches the predeterminedhigh state of charge (406). The battery pack system can be balanced onceeach module has reached the predetermined high state of charge andbegins its charge/discharge oscillation.

Once all battery pack system modules within a battery pack system arecharged to the predetermined high state of charge, creating a balancedsystem, it can be contemplated that all of the battery pack systemmodules exhibit an oscillating state of charge simultaneously, throughpartial discharge to a hysteresis state of charge using the shuntresistors, then simultaneous charging until the predetermined high stateof charge can be again reached.

While these embodiments have been described with emphasis on theembodiments, it should be understood that within the scope of theappended claims, the embodiments might be practiced other than asspecifically described herein.

1. A system for balancing a plurality of battery pack system modulesconnected in series, the system comprising: a plurality of battery packsystem modules connected in series, wherein a high charge module of theplurality of battery pack system modules has a charge greater than acharge for other modules of the plurality of battery pack system modulesconnected in series; at least one zener diode connected in series with acurrent limiting resistor and connected in parallel with the pluralityof battery pack system modules, wherein the at least one zener diode isdisposed between the high charge module and an adjacent module of theplurality of battery pack system modules, and wherein the at least onezener diode is in communication with a disconnect circuit of at leastone of the battery pack system modules; and a power source incommunication with the disconnect circuit of the at least one of theplurality of battery pack system modules, wherein the disconnect circuitis actuated when the at least one of the plurality of battery packsystem modules reaches a predetermined state of charge; wherein currentfrom the power source is limited by the current limiting resistor; andwherein the at least one zener diode enables current from the powersource to bypass at least one charged battery pack system module tocharge at least one other battery pack system module.
 2. The system ofclaim 1, wherein each battery pack system module of the plurality ofbattery pack system modules comprises: at least one balancing circuitcomprising a shunt resistor and a bypass switch, wherein the at leastone balancing circuit is in communication with a plurality of cellsconnected in series; at least one disconnect circuit comprising a chargeswitch, wherein the at least one disconnect circuit is in communicationwith the plurality of cells; and a controller assembly in communicationwith the plurality of cells connected in series, the controller assemblycomprising: a digital controller comprising a processor; means formonitoring and measuring parameters for the plurality of cells todetermine a state of charge for each cell of the plurality of cells; andcomputer instructions for instructing the processor to actuate andde-actuate the at least one balancing circuit, the at least onedisconnect circuit, or combinations thereof, responsive to theparameters for the plurality of cells.
 3. The system of claim 2, whereineach battery pack system module further comprises a protective diodeconnected to the plurality of cells connected in series and to the atleast one disconnect circuit, wherein the protective diode is a reversevoltage protection diode or a bypass diode.
 4. The system of claim 2,wherein the at least one discharge circuit further comprises a dischargeswitch.
 5. The system of claim 2, wherein the controller assemblyfurther comprises: computer instructions for instructing the processorto actuate and de-actuate the charge switch of the disconnect circuitwhen the battery pack system module reaches a predetermined state ofcharge; and computer instructions for instructing the processor toactuate and de-actuate the bypass switch of each at least one balancingcircuit to at least partially discharge the battery pack system modulewhen the battery pack system module reaches the predetermined state ofcharge.
 6. The system of claim 2, wherein the controller assemblyfurther comprises configuration memory with design parameters andcomputer instructions for instructing the processor to customizespecifications of the battery pack system module using the designparameters.
 7. The system of claim 2, further comprising a displaydevice in communication with the controller assembly, wherein thecontroller assembly further comprises computer instructions forinstructing the processor to display the state of charge of each batterypack system module on the display device.
 8. The system of claim 7,wherein the display device comprises a member of the group consistingof: a plurality of light emitting diodes, a liquid crystal display, aplasma display, and combinations thereof.
 9. The system of claim 7,wherein the controller assembly further comprises computer instructionsfor instructing the processor to display an absolute state of charge forthe battery pack system module by counting coulombs.
 10. The system ofclaim 1, wherein the power source comprises a rechargeable battery. 11.The system of claim 10, wherein the rechargeable battery comprises amember of the group consisting of: a lithium ion battery, a nickelcadmium battery, a nickel metal hydride battery, a lead acid battery,and combinations thereof.
 12. The system of claim 1, wherein at leastone of the battery pack system modules comprises at least one capacitor,at least one supercapacitor, at least one other electrochemical cell, orcombinations thereof.
 13. The system of claim 1, wherein at least one ofthe battery pack system modules comprises a plurality of battery packsystem modules connected in parallel.
 14. The system of claim 13,wherein the plurality of battery pack system modules connected inparallel are further connected in series.
 15. The system of claim 1,wherein at least one of the battery pack system modules is individuallyreplaceable.
 16. The system of claim 14, wherein at least one pluralityof battery pack systems module is individually replaceable.
 17. A systemfor balancing a plurality of battery pack system modules connected inseries, the system comprising: a plurality of battery pack systemconnected in series, wherein a high charge module of the plurality ofbattery pack system modules has a charge greater than a charge for othermodules of the plurality of battery pack system modules connected inseries; wherein each battery pack system module of the plurality ofbattery pack system modules comprises: at least one balancing circuitcomprising a shunt resistor and a bypass switch, wherein the at leastone balancing circuit is in communication with a plurality of cellsconnected in series; at least one disconnect circuit comprising a chargeswitch, wherein the at least one disconnect circuit is in communicationwith the plurality of cells; a controller assembly in communication withthe plurality of cells connected in series, the controller assemblycomprising: a digital controller comprising a processor; means formonitoring and measuring parameters for the plurality of cells todetermine a state of charge for each cell of the plurality of cells;computer instructions for instructing the processor to actuate andde-actuate the at least one balancing circuit, the at least onedisconnect circuit, or combinations thereof, responsive to theparameters for the plurality of cells; computer instructions forinstructing the processor to actuate and de-actuate the charge switch ofthe disconnect circuit when the battery pack system module reaches apredetermined state of charge; and computer instructions for instructingthe processor to actuate and de-actuate the bypass switch of each atleast one balancing circuit to at least partially discharge the batterypack system module when the battery pack system module reaches thepredetermined state of charge; and a power source in communication withthe at least one disconnect circuit, wherein the at least one disconnectcircuit and the at least one balancing circuit are actuated when atleast one of the plurality of battery pack system modules reaches thepredetermined state of charge enabling at least partial discharge of theat least one of the plurality of battery pack system modules andenabling charging of at least one other of the plurality of battery packsystem modules.
 18. The system of claim 17, wherein the computerinstructions for instructing the processor to actuate and de-actuate thebypass switch of each at least one balancing circuit further instructthe processor to actuate the bypass switch when the battery pack systemmodule is charged to a predetermined high state of charge, and tode-actuate the bypass switch when the battery pack system module isdischarged to a predetermined hysteresis charge.
 19. The system of claim17, further comprising: at least one zener diode connected in serieswith a current limiting resistor and connected in parallel with theplurality of battery pack system modules, wherein the at least one zenerdiode is disposed between the high charge module and an adjacent moduleof the plurality of battery pack system modules, wherein the at leastone zener diode is in communication with a disconnect circuit of atleast one of the battery pack system modules, wherein current from thepower source is limited by the current limiting resistor; and whereinthe at least one zener diode enables current from the power source tobypass at least one charged battery pack system module to charge atleast one other battery pack system module.